1. Field of the Invention
The invention relates to a mixing device for blending a developer composed of carrier particles and toner including a first and second mixing screw.
2. Description of the Prior Art
Mixing devices of the type described above are generally known and have been successfully employed. German Letters Patent No. 31 17 309 discloses a mixing device for blending a developer composed of carrier particles and toner which is employed in the developing station of a printer functioning in accord with the electrophotographic principle.
Given this mixing device functioning based on the principle of cross-blending, the resupplied toner is added to the developer in the mixing trough over the full length and is supplied to the developing process at one side at the end of the mixing trough. Since the developer mix enriched with the supplied toner has a higher toner concentration than the remaining developer, a non-uniform toner concentration distribution in the developing region derives due to the single-sided feed of the developer enriched with toner, As a consequent thereof, inadmissibly high inking differences over the printed width can occur. This negative effect becomes especially pronounced given weak inking, high printing format load and when printing bar codes.